1. Field of the Invention
The present invention relates to an inkjet head for performing recording by ejecting liquid such as ink to a medium to be recorded, and a method of manufacturing the inkjet head.
2. Description of the Related Art
In an inkjet head applied to an inkjet recording system, various proposals have been made for enhancing performance such as higher image quality and higher printing speed. Regarding the water-repellent treatment of a nozzle surface, Japanese Patent Application Laid-Open No. 2003-300323 proposes a method of improving printing quality by providing water-repellent and non-water-repellent areas on the surface of an ejection orifice. In the case where the entire surface of the ejection orifice is made water-repellent, ink mist may accumulate during continuous printing or the like to form ink droplets, which are taken into the ejection orifice to cause non-ejection of ink. Japanese Patent Application Laid-Open No. 2003-300323 discloses that, when a hydrophilic portion is provided partially on the surface of the ejection orifice, ink mist accumulates in the hydrophilic portion, which can prevent the take-in of ink droplets to the ejection orifice. Japanese Patent Application Laid-Open No. 2007-518587 uses a cured condensation product formed of a hydrolyzable silane compound having a fluorine-containing group and a hydrolyzable silane compound having a cationically polymerizable group as a water-repellent layer. By setting a mask pattern and an exposure condition appropriately, only a water-repellent layer can be removed partially except a portion in which an ejection orifice is formed. That is, when a mask pattern is less than a resolution limit, only a water-repellent layer is removed partially.
However, in the case where recording is performed at high printing speed and high duty in continuous long-term high-frequency driving, a great amount of ink mist is generated. Thus, in the case of using a conventional inkjet head having a hydrophilic portion in which only the water-repellent layer is partially removed, a great amount of ink mist accumulates in the hydrophilic portion. When ink droplets become so large that the ink droplets cannot be held in the hydrophilic portion, the ink droplets may be taken into the ejection orifice to cause non-ejection.